So far, the blend filters used on all ISIs didn't provide isolation (even a light motion increase) around 500mHz (the first pitch mode of the QUAD at 0.44Hz causes trouble to ISC). I installed new blend filters (blend frequency at 100mHz with a notch at 440mHz). I have attached the LP blend filters used yesterday night and the new ones (called T100mHZ_0.44). They shoud provide a factor 10 isolation at 0.44Hz.